In order to analyze the reason of cracking occurred in the superheater lutlet header,some experiments were carried out.The result showed that the hydrogen induced cracking (HIC) was the main reason of the failure,and the impingement corrosion accelerated the cracking process. In order to analyze the reason of cracking occurred in the superheater lutlet header, some experiments were carried out. The result showed that the hydrogen induced cracking (HIC) was the main reason of the failure, and the impingement corrosion accelerated the cracking process.